Pressure-medium-actuated clutch

Abstract

A pressure-medium actuated clutch that includes a plurality of clutch disks and a piston slidably positioned for movement toward and away from the disk to selectively engage and to disengage the clutch. A pressure chamber is provided adjacent to the piston and communicates with a source of pressurized fluid. A pilot-pressure-operated control valve is provided to control the pressure of the pressurized fluid, and a flow constriction is provided in a conduit extending from the control valve to the pressure chamber. A method for actuating the clutch is also disclosed.

What is claimed is:  
     
       1. A pressure-medium-actuated clutch comprising: an annular pressure plate slidably supported for movement toward and away from a plurality of clutch disks, the pressure plate including a piston surface that is spring biased toward a disengaged condition of the clutch; a pressure chamber formed adjacent to and facing the piston surface, wherein the pressure chamber is adapted to receive pressurized fluid to cause the piston surface and pressure plate to move toward an engaged condition of the clutch; a pressure-medium control system including at least one pilot-pressure-controlled valve, wherein, at the beginning of actuation with a substantially unpressurized pressure chamber the chamber is filled more quickly at higher pressure; and control means operable upon reaching one of a desired pressure in the pressure chamber and a predetermined time interval to fill the pressure chamber with fluid more slowly, wherein the pressure plate includes a generally radially-extending pressure surface and an annular wall member extending axially, an inner clutch disk carrier surrounding the annular wall member, and a bearing carried between the annular wall member and the disk carrier to minimize frictional resistance to axial movement of the pressure plate. 
     
     
       2. A pressure-medium-actuated clutch in accordance with  claim 1 , including a flow constriction positioned between the pressure chamber and the pressure-medium control system. 
     
     
       3. A pressure-medium actuated clutch in accordance with  claim 2 , wherein the pressure in the pressure chamber is set by a proportional valve. 
     
     
       4. A pressure-medium-actuated clutch in accordance with  claim 1 , wherein the bearing is a ball bearing. 
     
     
       5. A pressure-medium-actuated clutch in accordance with  claim 4 , wherein the clutch disk carrier includes a plurality of axially-extending grooves that define a bearing track, and wherein the bearing is carried in a recess formed in the annular wall member and radially opposite the bearing track. 
     
     
       6. A pressure-medium-actuated clutch in accordance with  claim 5 , wherein the bearing track is defined by a pair of circumferentially-spaced, axially-extending teeth. 
     
     
       7. A pressure-medium actuated clutch in accordance with  claim 1 , wherein the valve includes a valve spool having a control surface against which fluid pressure acts to provide a force in opposition to a pilot pressure force. 
     
     
       8. A pressure-medium-actuated clutch in accordance with  claim 7 , wherein the valve includes a feedback loop for conveying valve outlet pressure to the control surface.